How to Make an Arch in Your Entryway

Remove any molding and cut away the existing drywall from around the entryway where you are installing the arch. Cut away enough drywall to expose the wood framing beneath it. You can use a utility knife to cut through drywall, but be careful of the screws that are holding it in place.

Make a pattern and template out of cardboard in the shape of the arch you wish to create. Hold the cardboard arch up to the entrance way and check that it is exactly what you want. The template should be what the arch itself will look like, meaning the concave part, not the part of the entrance way you want removed.

Trace two copies of the template onto the 1/2-inch-thick sheet of plywood. Cut out the two pieces using a jigsaw.

Mount one of the plywood arch frames to the framework that was exposed when you removed the drywall. Have a friend hold the plywood arch in place. Then, using drywall screws, fasten the upper corners of the arch to the framework. Fasten the remainder of the arch, placing drywall screws every 3 to 5 inches. Mount the other plywood arch frame in the same manner. These two panels will become the arch itself, so be sure they are positioned the way you want them.

Measure the distance between the two plywood arches, and cut a number of 2-by-4's to this length. You should have enough 2-by-4's to space them 4 to 6 inches apart. For example, if your arch spanned 4 feet, you would need about 6 pieces.

Install the 2-by-4 pieces by placing them between the plywood arch templates along the arch edge. Fasten them by screwing through the plywood into the ends of the blocks. This should create a rough arch the shape and depth you want.

Measure and cut two 1/2-inch-thick drywall arches that will cover the plywood templates completely. Use the cardboard template from Step 2. Mount the drywall arches to the plywood using some drywall screws.

Measure the length of your arch, following along the curve. Measure the distance between the outside edges of the drywall you installed in Step 7. On the 1/4-inch flexible drywall, draw a rectangle to these dimensions. Cut out the rectangle.

Install this drywall strip under the arch. Screw it into the 2-by-4 blocks you installed between the plywood arches.

Cover the rough edges of the arch with drywall tape. Mix or otherwise prepare the drywall plaster and apply it evenly over the drywall surfaces to hide and fill in any gaps or rough edges. As this is an interior archway, do not be overly concerned with the strength of the plastering, as it will not be exposed to the elements.

Allow the plaster to set before sanding and filling any final gaps, and then paint to match the hallway.